Coating metals with zinc



2 Sheets -Sheet 1.

(No Model.)

H. ROBERTS.

COATING METALS WITH ZINC.

Patented Aug. 1, 1882.

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ATENT F FICEQ HENRY ROBERTS, OF JOHNSTOWN, PENNSYLVANIA.

COATING METALS WITH ZINC.

SPECIFICATION forming part of Letters Patent No, 262,124, dated August1, 1882, Application filed December 17,1880. (No model.)

To all whom it may concern:

Be it known that I, HENRY ROBERTS, a citizen of the United States,residing at Johnstown, Gambria county, in the State of Pennsylvania,have invented certain new and useful Improvements relating to CoatingMetals with Zinc, of which the following is a specification.

Theinventionappliesto thecoatingofwires, ordinarily so called, whetherround or flat, and also to extended lengths in various other forms, ashoop-iron, &c. There is a tendency of the zinc to become deteriorated inquality by a long subjection to the passage of the wire or analogouslength of the iron or other metal to be coated. I will describe theprocess as applied to thetreatment of common round wires, which I willassume are drawn down from rolled rods of Bessemer steel; but itmay beunderstood that any metal capable of being coated with 'zinc oranalogous metal may be substituted,

and that the wires may be flat, round, or of various other sections, andthat they may be known as wires" or by the various other technicalnames, as hoop-iron, bale-ties, or the like.

I provide a long bath of melted zinc, with the heating-fires around theexterior, and the bottom relatively cool for the subsidence of what isknown as dross. I provide the ordinary surtace-coating of sal-ammoniacand the ordinary immersing-sinker, beneath which the wires are passedthrough the bath in order to insure their long and uniform immersion. Iprovide peculiarly-efficient means for wiping off the surplus metal andfor insuring a succession of fresh surfaces ofthe wiping material. Iattain this end by leading the wires in an inclined direction upwardfrom the bath through a mass of suitable wiping material, which isconstantly moved in a direction opposite to that of the wires. Thewiping being effected in this manner and immediately on the emergence ofthe wires from the melted bath I can reduce the consumption of zinc to aminimum, and insure that it is left with more than ordinary uniformityof thickness. I have also improved the wiping by the application of amaterial hitherto unused for the purpose. It is what is known asslag-wool or silicate cottona silky, fibrous matter produced by thetreatment of cinder from a blast-furnace by blowing out with a currentof steam at high pressure. It is highly elastic and soft, and is notdestroyed by the heat, has a just sufficient property of adhesion to themelted metal or wiping power, and is sufficiently mobile in itsof theordinary and long-approved character.

The accompanying drawings form a part of this specification, andrepresent what I consider the best means of carrying out the invention.

Figure 1 is a vertical section through the entire apparatus. Fig. 2 is aplan view of the same. Theremainingfigures representdetails detached.Fig. 3 is a central vertical section of my improved wiping-box. Fig. 4is a plan view of a portion of the same, showing the ends of theagitating-rolls, their operatinggear, and the partition-space at theside.

Similar letters of reference indicate like parts in all the figures.

I have shown but one wire.

A is the reel, from which the wire at is delivered; B, the acid bath; 0,a quantity of broken stone therein; D, a series of rolls, some of whichare preferably turned by power to aid the movement of the wire; E, aguiding-sheave; F, tubes through the drying-furnace G; and H, a seriesof guiding-sheaves, from which the wire is plunged directly into thebath I of melted metal.

J J 'are sinkers in the melted metal, so placed that the wires inpassing under these sinkers are certain of being immersed to the properdepth. The tank is of sufficient length to insure auniformity oftemperature between the wires and the bath before the wires emerge. Ihave in my experiments made the metaltank I about twelve (12) feet long,and caused the wires to traverse a little over a foot per second. Thesinkers J are peculiar. There is one of these for each wire. Each has atits upper end an outwardly-projecting lug, which is just the right sizeto engage in graduated holes in a bridge or piece spanning the end ofthe tank. On emerging from the metal bath I the wires are led up throughslots in the bottom of a partially-overhanging box, K, which contains aliberal supply of the slag-wool 7c, which serves as the wiping material,and should be kept damp with water or tungstate of soda. The wires areled in an inclined direction through this box, and emerge with just asufiicient coating of zinc. The required circulating movement of thewiping material is attained by rollers L, mounted in the wiping-box, andturned by gearing in the directions indicated by thearrows. The surfacesof the several rolls are armed with projections l, which engage with ajust suflieient quantity of the slag-wool, and drag it along in thedirection opposite to the movement of the wires m. The

. rollers are turned slowly-only about one revolution in two seconds.They agitate the slagwool and continually present new surfaces thereofto the steadily-moving wires. The general tendency of the rollers is tomove the slag-wool gradually from the back to the front of thewiping-box, or, in other words, toward that side of the wiping-box whichoverhangs the tank. The slag-wool is in its nature a good non-conductor.Its temperature is soon raised by the working, so that it approximatesclosely to that of the melted zinc, except that the upper stratum iskept wet and relatively cool by sprinkling with water, either ordinaryfresh water or preferably a solution of tungstate of soda. The meltedzinc removed by the particles of slag-wool, and moved actively towardthe receiving side of the box, is deposited in that edge of the box anddropped through the slots there provided into the tank. The aflinity oradhesion of the melted metal to the earthy wool is very slight.

Instead of accumulating and becoming densely compacted in the receivingside of the wiping-box, I take measures to produce a circulation of thematerial. It is worked under and over the several rollers. Each rollerof each pair carries the slag-wool toward the tank on one side, where iteffects the wiping, and away from it on the other side, where itis-returning idly.

P is an additional roll, of which I can use more than one, if necessarybut my experiments do not indicate such need to aid in transferring thefibrous material from that end of the box toward the back or moredistant side of the box. The result is a constant agitation of thewiping material, and a presentation of afresh surface to the meltedmetal coating on the wire, also a movement of the material between therolls toward the receiving side of the box, and thence upward andbackward to the other side of the box, where it is again moved forward.I believe that thelowermost rollers of each pair also carry a liberalcurrent of the slag-wool downward, and move it backward in the base ofthe box; but of this I have not so well assured myself. Mineral wool isjust sufiiciently elastic and glassy in its nature. The action of therolls not only presents fresh surfaces, and presents them with a motionopposite to that of the wires, so as to insure an effective wiping, butalso tends to induce a quite compact condition of the fibrous materialat the base of the receiving side of the wiping-box. It tends the betterto express any particles of melted metal which have been brought with itfrom the other portions of the box. I esteem this a marked advantage.

The journals of the several rollers L l are of considerable length, andproject through two walls, which I provide in each end of thewiping-box, with an air-space between. This facilitates access forexamination and oiling, and tends to prevent the induction of heat.

The lower portion of the side of the wipingbox nearest to the tank ofmelted metal is made in a separate piece from the rest, and can beremoved on taking out the screws, which are inserted through lugs in theupper portion of the side. This facilitates the removal of thefinely-broken wiping material which tends to accumulate there.

Modifications may be made in the forms and proportions of the details.

I have worked successfully with the wipingbox only about two (2) feetwide, so as to give a wiping traverse of only two (2) feet; but this maybe varied. I believe that little gain would result from an increase ofthe wipingtraverse, because wires of small size become rapidly cooled.For very large wires a wider wiping-box would be expedient.

Instead of slots to receive the wires in the overhanging portion ofthewiping-box K, I can use plain round holes; but I esteem slotspreferable. There is a tendency of the slag-wool to become worn,abraded, or broken, so as to accumulate a fine dust in the bottom. Whenthis has become too fine I replace it with fresh. No particularditficulty is experienced if considerable of the broken earthy matterfalls upon the melted zine.

The dotted circles represent the gearing bywhich the rolls L are turned.I have not deemed it necessary to represent the belt through which themotion is received. I mount them in two independent trains, in orderthat I can, if preferred, after the operation has fairly commenced,arrest the motion ot'the rolls which are farthest from the metal bathand operate the remainder.

The mineral wool which I employ possesses the same capacity for wipingoff the surplus metal from the wire as the various fibrous materialsheretofore employed for that purpose, and it acts as efliciently, while,by reason of its mineral character and its capacity to endure a hightemperature, it is not destroyed or seriously affected by the hot zinc,and can perform indefinitely for a long period. The movement of themineral wool loaded with the metal toward the tank, with the provisionsfor its easy escape therefrom to fall into the tank I claim as myimprovement in zinc-coating wires-Themethodot'removingthesurplusofmelted metal from the wires on emergingfrom the bath by working the wiping material k, so as 20 to presentconstantly fresh surfaces, substantially as herein specified.

In testimony whereofI have hereunto set my hand, at New York city, this7th day of December, 1880, in the presence of two subscrib- 2 ingwitnesses.

HENRY ROBERTS. Witnesses:

W. OoLBoRNE BROOKS, H. A. J onns'ronn.

